Cast Singularity Rapture by paying {3}{U}{B}{B}, destroying all creatures and then causing any number of target players to mill a number of cards equal to half their library, rounded down, times two.

Infinite mill

Infinite self-mill

Bruvac the Grandiloquent

Singularity Rupture

Cast Singularity Rupture with kicker by paying {4}{U}{U}, causing each opponent to mill half their library, rounded up.
Activate Riverchurn Monument's exhaust ability by paying {2}{U}{U} and tapping it, causing each opponent to mill the remainder of their library.

Combos with "Singularity Rupture"